U.S. patent application number 11/115962 was filed with the patent office on 2005-11-03 for differential carrier assembly.
Invention is credited to Gianone, Roberto, Magnago, Clemente, Pontanari, Marco.
Application Number | 20050245342 11/115962 |
Document ID | / |
Family ID | 32408141 |
Filed Date | 2005-11-03 |
United States Patent
Application |
20050245342 |
Kind Code |
A1 |
Pontanari, Marco ; et
al. |
November 3, 2005 |
Differential carrier assembly
Abstract
A differential carrier assembly includes a differential carrier
and a differential casing having a ring gear that is supported on
right and left differential bearings for rotation about a
differential axis. The right and left differential bearings are
each supported in respective right and left bearing housings. A
pinion having a pinion gear meshes with the ring gear and includes
a spigot positioned on a differential axis side of the pinion gear.
The spigot is supported in a spigot bearing, and the spigot bearing
is supported in a spigot bearing housing. One of the right or left
bearing housings and the spigot bearing housing are formed on a
common component which is separate from and securable to the
differential carrier.
Inventors: |
Pontanari, Marco; (Riva del
Garde (TN), IT) ; Gianone, Roberto; (Barengo (NO),
IT) ; Magnago, Clemente; (Trecate (NO), IT) |
Correspondence
Address: |
CARLSON, GASKEY & OLDS, P.C.
400 WEST MAPLE ROAD
SUITE 350
BIRMINGHAM
MI
48009
US
|
Family ID: |
32408141 |
Appl. No.: |
11/115962 |
Filed: |
April 27, 2005 |
Current U.S.
Class: |
475/230 |
Current CPC
Class: |
F16H 2048/382 20130101;
F16H 48/08 20130101; F16H 48/42 20130101; F16H 48/40 20130101; F16H
2048/385 20130101; F16H 2048/423 20130101; F16H 2048/405 20130101;
F16H 2048/426 20130101; F16H 57/021 20130101; F16H 57/037
20130101 |
Class at
Publication: |
475/230 |
International
Class: |
F16H 048/06 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 28, 2004 |
GB |
0409418.1 |
Claims
What is claimed is:
1. A differential carrier assembly comprising: a differential
carrier including a pinion shaft bearing arrangement housing; a
differential casing including a ring gear and supported on a right
differential bearing and a left differential bearing for rotation
about a differential axis, wherein the right differential bearing
and the left differential bearing are supported in a right bearing
housing and a left bearing housing, respectively; and a pinion
including a pinion gear in meshing engagement with the ring gear, a
spigot positioned on a differential axis side of the pinion gear,
and a pinion shaft positioned on an opposite side of the pinion
gear from the spigot, wherein the spigot is supported in a spigot
bearing that is supported in a spigot bearing housing, and the
pinion shaft is supported in a pinion shaft bearing arrangement
that is supported in the pinion shaft bearing arrangement housing,
wherein the spigot bearing housing and one of the right bearing
housing and the left bearing housing are formed on a common
component which is separate from and securable to the differential
carrier.
2. The differential carrier assembly as defined in claim 1 wherein
the common component is formed as a unitary component.
3. The differential carrier assembly as defined in claim 2 wherein
the common component is formed from a casting.
4. The differential carrier assembly as defined in claim 1 wherein
the other of the right bearing housing and the left bearing housing
is formed as a separate component which is securable to the
differential carrier.
5. The differential carrier assembly as defined in claim 4 wherein
the separate component is securable to the differential carrier by
lugs.
6. The differential carrier assembly as defined in claim 1 wherein
the common component includes lugs to secure the common component
to the differential carrier.
7. The differential carrier assembly as defined in claim 1 wherein
the common component includes a fixed bearing race shoulder, and an
outer race of an associated differential bearing abuts the fixed
bearing race shoulder.
8. The differential carrier assembly as defined in claim 1 wherein
the spigot bearing defines a pinion axis about which the pinion
rotates, the ring gear is mounted on one side of the pinion axis
and includes an array of teeth each having an apex that define a
tooth apex plane, the spigot bearing housing having a region on the
one side of the pinion axis, wherein the region of the spigot
bearing housing is spaced further from the pinion axis than the
tooth apex plane.
9. A method of assembling a differential carrier assembly including
steps of supporting a differential casing including a ring gear on
a right differential bearing and a left differential bearing;
supporting the right differential bearing and the left differential
bearing in a right bearing housing and a left bearing housing,
respectively; rotatably mounting a pinion including a pinion shaft,
a spigot, and a pinion gear located between the pinion shaft and
the spigot in a differential carrier including a pinion shaft
bearing arrangement housing via a pinion shaft bearing arrangement;
mounting a spigot bearing on or in one of the spigot and a spigot
bearing housing; forming the spigot bearing housing and one of the
right bearing housing and the left bearing housing on a common
component which is separate from and securable to the differential
carrier; mounting the differential casing on the differential
carrier; meshing the ring gear with the pinion gear; and mounting
the spigot bearing on or in the other of the spigot and the spigot
bearing housing; and securing the common component to the
differential carrier.
10. The method of as defined in claim 9 wherein the steps of
supporting the differential casing and supporting the right
differential bearing and the left differential bearing are carried
out remotely from the differential carrier.
11. The method as defined in claim 9 wherein the spigot bearing
defines a pinion axis about which the pinion rotates, the ring gear
is mounted on one side of the pinion axis and the ring gear
includes an array of teeth each having an apex defining a tooth
apex plane, wherein a region of the spigot bearing housing on the
one side of the pinion axis is spaced further from the pinion axis
than the tooth apex plane.
12. The method as defined in claim 9 wherein the step of mounting
the differential casing is carried out at substantially the same
time as the step of mounting the spigot bearing.
13. The method as defined in claim 9 including the steps of
providing the other of the right bearing housing and the left
bearing housing as a separate component and securing the separate
component to the differential carrier.
14. The method as defined in claim 13 wherein the common component
includes a bearing race shoulder, the separate component includes a
threaded portion, and a bearing preload ring has a ring thread that
engages a thread in the threaded portion, the method further
including the step of adjusting the bearing preload ring to provide
a correct preload in the right differential bearing and the left
differential bearing between the bearing preload ring and the
bearing race shoulder.
15. The method as defined in claim 9 wherein the step of rotatably
mounting is carried out before the step of securing.
16. The method as defined in claim 9 wherein the step of rotatably
mounting includes inserting the pinion shaft into the pinion shaft
bearing assembly housing from a differential casing side of the
pinion shaft bearing assembly housing.
Description
REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to United Kingdom Patent
Application GB 0409418.1 filed on Apr. 28, 2004.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to differential carrier
assemblies.
[0003] Known differential carrier assemblies include several
components, the primary components being a differential carrier, an
input pinion, a ring gear and a differential casing. Various
components are mounted on bearings, and it is important to ensure
the correct pre-load on certain bearings during assembly. It is
also important to ensure the correct back lash between the ring
gear and the input pinion. Thus, it is necessary to ensure that the
input pinion is positioned longitudinally (relative to the pinion
axis) correctly relative to the ring gear. It is also important to
ensure that the ring gear is correctly positioned laterally
(relative to the input pinion axis). For these reasons, the correct
assembly of a differential carrier is time consuming, complicated,
and therefore expensive.
[0004] In particular, it is known to have an input pinion having a
pinion gear mounted between a pinion shaft and a spigot. The spigot
(which is on the differential casing side of the pinion gear) is
rotatably mounted in a spigot bearing which in turn is mounted in a
spigot bearing housing. The pinion shaft is also mounted in
bearings which again are mounted in a pinion shaft bearing housing.
The spigot bearing housing and the pinion shaft bearing housing are
formed in an integral component and as such the pinion shaft
bearing housing must be large enough to allow the pinion gear to
pass therethrough during assembly. Such an arrangement is shown in
U.S. Pat. No. 5,520,589, GB1545004, GB226717, GB 1247751 and FIG. 2
of U.S. Pat. No. 5,203,750. Such arrangements either require a
large internal diameter for the pinion shaft bearing housing and/or
the outer diameter of the pinion gear teeth to be machined away (as
shown in FIG. 2 of U.S. Pat. No. 5,203,750) to ensure the pinion
gear fits through the pinion shaft bearing housing.
[0005] Alternatively, the pinion can be assembled into the pinion
shaft bearing assembly housing from the differential casing side.
Under these circumstances, the diameter of the pinion gear can be
larger than the internal diameter of the pinion shaft bearing
assembly housing. However, the spigot bearing housing must be
provided as a separate component to ensure the components can be
assembled. Such an arrangement is shown in U.S. Pat. No. 4,526,063
and FIG. 1 of U.S. Pat. No. 5,203,750. However, in both these
embodiments, the pinion shaft bearing assembly housing is
integrally formed with the right and left differential bearing
housing and hence the differential bearing housings are formed on a
separate component to the spigot bearing housing.
SUMMARY OF THE INVENTION
[0006] An object of the present invention is to provide a
differential carrier assembly that is easier to assemble. Another
object of the present invention is to provide a differential
carrier assembly that requires less adjustment to correctly
assemble. Another object of the present invention is to provide a
differential carrier assembly that is easier to machine.
[0007] Thus, according to the present invention, a differential
carrier assembly includes a differential carrier having a pinion
shaft bearing arrangement housing. A differential casing including
a ring gear is supported on right and left differential bearings
for rotation about a differential axis. The right and left
differential bearings are each supported in respective right and
left bearing housings. The differential carrier assembly also
includes a pinion having a pinion gear in meshing engagement with
the ring gear and a spigot positioned on a differential axis side
of the pinion gear. A pinion shaft is positioned on a side of the
pinion gear opposite from the spigot. The spigot is supported in a
spigot bearing, and the spigot bearing is supported in a spigot
bearing housing. The pinion shaft is supported in a pinion shaft
bearing arrangement, and the pinion shaft bearing arrangement is
supported in the pinion shaft bearing arrangement housing. The
spigot bearing housing and one of the right or left bearing
housings are formed on a common component which is separate from
and securable to the differential carrier.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The invention will now be described, by way of example only,
with reference to the accompanying drawings in which:
[0009] FIG. 1 is an isometric view of an axle assembly including a
differential carrier assembly according to the present
invention;
[0010] FIG. 2 is a plan cross section view of the differential
carrier assembly of FIG. 1;
[0011] FIG. 3 is a differing view of a differential bearing housing
and a pinion spigot bearing housing formed on a common
component;
[0012] FIG. 4 is a differing view of the differential bearing
housing and the pinion spigot bearing housing formed on the common
component;
[0013] FIG. 5 is a differing view of the differential bearing
housing and the pinion spigot bearing housing formed on the common
component;
[0014] FIG. 6 is a view of a differential bearing housing formed on
a separate component; and
[0015] FIG. 7 is a view of a differential carrier.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0016] FIG. 1 shows a drive axle 10 which includes a pair of axle
shafts 12 (only one of which is shown) for driving wheels (not
shown) secured to wheel hubs 14. When the vehicle is driven along a
straight path, the wheel hubs 14 turn at approximately the same
speed, and the drive torque will be equally split between both
wheels. When the vehicle turns, the outer wheel has to travel over
a greater distance than the inner wheel. A differential assembly 16
allows the inner wheel to turn more slowly than the outer wheel as
the vehicle turns.
[0017] Power is transmitted from an engine and transmission (not
shown) to the drive axle 10 via a longitudinally extending drive
shaft (not shown). The drive shaft is coupled to an input pinion 18
via a yoke assembly 20. The input pinion 18 is in constant mesh
with a differential ring gear 22. As shown in FIG. 2, the
differential ring gear 22 is bolted (via bolts 86 and nuts 86A) to
a differential casing 24 that turns with the differential ring gear
22.
[0018] A differential spider 26 includes four support shafts 28
(only two of which are shown) that are orientated in the shape of a
cross. One differential pinion gear 30 is supported for rotation on
each support shaft 28. Power is transferred from the differential
casing 24 to side gears 82 that are splined to the axle shafts 12.
The side gears 82 are in constant mesh with the differential pinion
gears 30. The outer ends of the axle shafts 12 are bolted to the
wheel hubs 14. An axle housing 25 is used to enclose and protect
the differential assembly 16, the gearing and the axle shafts 12.
In particular, the axle housing 25 and a differential carrier 60
(see below) completely enclose a common component 70 (see below)
and a separate component 76 (see below).
[0019] When the vehicle is driven in a straight path, the
differential ring gear 22, the differential casing 24, the
differential spider 26, the differential pinion gears 30 and the
side gears 82 all rotate as one unit to transfer power to the axle
shafts 12. There is no relative movement between the differential
pinion gears 30 and the side gears 82. When the vehicle turns, the
differential pinion gears 30 rotate on their respective support
shafts 28 to speed up the rotation of one axle shaft 12 while
slowing the rotation of the other axle shaft 12.
[0020] FIG. 2 shows the input pinion 18 including a pinion shaft
40, a pinion gear 42 having pinion teeth 43 and a pinion spigot 44.
The input pinion 18 is rotatably mounted about a pinion axis A via
a pinion shaft bearing arrangement which includes taper roller
bearings 46 and 48. Outer races 46A and 48A of the taper roller
bearings 46 and 48 are mounted in a housing 62 of a differential
carrier 60. A land 64 acts to space apart the outer races 46A and
48A. A spacer 50 spaces apart the inner races 46B and 48B of the
taper roller bearings 46 and 48. The pre-load on the taper rolling
bearings 46 and 48 can be adjusted by varying a length of the
spacer 50 (typically by substituting a different spacer having a
different length).
[0021] The differential ring gear 22 includes an array of gear
teeth 23 and rotates about an axis B (as will be further described
below). It is important to set the pinion gear 42 at the correct
position relative to the axis B. This can be done by providing
thicker or thinner shims 52 positioned between the land 64 and
outer race 48A.
[0022] The pinion spigot 44 is supported in a spigot bearing 54,
which in turn is mounted in a spigot bearing housing 56 (see in
particular FIG. 3).
[0023] The differential casing 24 is formed from two halves 24A and
24B which are bolted together via bolts 92. A differential casing
sub assembly 34 is provided, the major components of which are the
differential casing halves 24A and 24B, the differential ring gear
22, the differential spider 26, the differential pinion gears 30,
the bolts 92, the bolts 86 and the associated nuts 86A and the side
gears 82.
[0024] The differential casing sub assembly 34 is mounted via a
right differential bearing 94 and a left differential bearing 96.
Each differential bearing 94 and 96 includes a differential bearing
outer race 94A and 96A mounted in respective right and left
differential bearing housings 98 and 99. Differential bearing inner
races 94B and 96B are mounted on projections of differential casing
halves 24B and 24A, respectively.
[0025] FIGS. 3 to 5 show the right hand differential bearing
housing 98 and the spigot bearing housing 56 which have been
combined onto a common component 70. In this case, the common
component 70 has been formed as a unitary component and furthermore
has been machined from a single casting. The common component 70
includes lugs 71A and 71B having holes 72A and 72B through which
bolts (not shown) can pass and engage with threaded holes 63A and
63B of the differential carrier 60, thereby securing the common
component 70 to the differential carrier 60.
[0026] The common component 70 further includes centering abutment
surfaces 73A and 73B which engage with corresponding abutment
surfaces (not shown) of the axle housing 25 to help center the
differential carrier 60 relative to the axle housing 25. The common
component 70 further includes a bearing race shoulder 74 (best seen
in FIG. 2), the purpose of which will be described below.
[0027] FIG. 6 shows the left differential bearing housing 99 which
has been formed as a separate component 76. The separate component
76 includes lugs 77A and 77B having through holes 78A and 78B
through which bolts (not shown) can pass and engage with threaded
holes 64A and 64B of the differential carriers 60, thereby securing
the separate component 76 to the differential carrier 60. Centering
abutment surfaces 81A and 81B engage corresponding centering
abutment surfaces (not shown) of the axle housing 25 to help center
the differential carrier 60 relative to the axle housing 25. The
separate component 76 includes a threaded region 79 (only part of
which is shown in FIG. 6 for clarity). An externally threaded
bearing pre-load ring 80 threadingly engages the threaded region
79, and will be further described below.
[0028] Regions 65A and 65B of the differential carrier 60 that
surround the holes 64A and 64B are flat and lie in a common plane.
This provides a flat surface against which abutment surfaces of the
lugs 77A and 77B can engage. Similarly, regions 66A and 66B that
surround the threaded holes 63A and 63B are also flat and lie in a
common plane (though not necessarily common with the plane defined
by the regions 65A and 65B) to define abutment surfaces against
which corresponding abutment surfaces of the lugs 71A and 71B can
engage.
[0029] One method of assembling a differential carrier assembly is
as follows. The input pinion 18, the taper roller bearings 46 and
48, the spacer 50, the shim 52 and the yoke assembly 20 can all be
assembled into the differential carrier 60, and the pinion nut 41
can be tightened such that the pinion bearing pre-load is correct
and the axial position of the pinion gear 42 is correct. This
provides a differential carrier and pinion sub assembly 61.
[0030] Separately, the differential casing sub assembly 34, as
described above, can be assembled. The differential bearing inner
races 94B and 96B can be mounted on appropriate differential casing
halves 24A and 24B, and the differential bearing outer races 94A
and 96B can be mounted in the appropriate common component 70 and
the separate component 76.
[0031] The right differential bearing outer race 94A is assembled
such that it engages the bearing race shoulder 74, and the bearing
pre-load ring 80 is loosely assembled into the threaded region 79.
The spigot bearing 54 is mounted in the spigot bearing housing 56
of the common component 70.
[0032] The common component 70 and the separate component 76 can
then be loosely assembled onto the differential casing sub assembly
34 to provide a differential casing and bearing housing sub
assembly 35 and can then be mounted onto the differential carrier
60. During the mounting of the differential casing and bearing
housing sub assembly 35, the pinion spigot 44 will engage the inner
race of the spigot bearing 54 at substantially the same time as the
gear teeth 23 of the differential ring gear 22 mesh with the pinion
gear teeth 43. Bolts can then pass through the holes 72A, 72B, 78A
and 78B and into the respective threaded holes in the differential
carrier 60 to releasably secure the common component 70 and the
separate component 76 to the differential carrier 60, thereby
securing the differential casing and bearing housing sub assembly
35. Once this has been done, the bearing pre-load ring 80 can be
tightened to set the correct pre-load in the differential bearings
94 and 96.
[0033] Prior art differential carrier assemblies have each
differential bearing housing formed as two parts. One part is
formed integrally with the differential carrier, and the other part
is formed as a half cap. This requires machining of the integral
part of the bearing housing, separate machining of the half cap,
the mating together of the half cap onto the integral part of the
bearing housing, and then subsequent finish machining. Since the
differential bearing housings of the present invention are not
formed in two halves, the machining of these components is
simplified.
[0034] Prior art differential carrier assemblies also include a
spigot bearing that is integral with the differential carrier
casting. This requires the carrier casting to be machined with
undercuts and other complex machining operations. The machining of
the spigot bearing of the present invention can be performed
separately from the machining of the differential carrier.
Therefore, the machining of the differential carrier is
significantly simplified, as is the machining of the spigot bearing
housing.
[0035] Because the spigot bearing housing 56 and the differential
bearing housing 98 can be machined on the common component 70 of
the present invention, the manufacturing tolerances between these
two components is significantly reduced. The tolerances are such
that the fixed bearing race shoulder 74 can be provided on the
common component 70, and a single bearing pre-load ring 80 can be
provided on the separate component 76. This simplifies assembly
since, in the prior art, each differential bearing had its own
associated bearing pre-load ring to enable the differential casing
to be positioned at the correct lateral position relative to the
pinion gear.
[0036] The differential ring gear 22 and the input pinion 18
perform two functions. First, they rotate the drive through 90
degrees, i.e., while the input pinion 18 rotates about the axis A,
the differential ring gear 22 rotates about the axis B, which is at
90 degrees relative to the axis A. Second, they provide a gear
reduction, i.e., the differential ring gear 22 rotates more slowly
than the input pinion 18.
[0037] Depending upon the particular application, different gear
reductions are required, and this can typically be achieved by
providing a different input pinion 18 and differential ring gear 22
set. FIG. 2 shows the profiles of three different differential ring
gears (22, 122 and 222). The gear teeth 23 of the differential ring
gear 22 each have a tooth apex 23B. The set of tooth apexes 23B
together define a plane C which is spaced by a distance Cl from the
axis A.
[0038] The apexes of the gear teeth 23 of the ring gear 122 define
a plane D which is spaced by a distance D1 from the axis A, and
similarly, the apexes of the teeth of the ring gear 222 define a
plane E which is spaced by a distance El from the axis A.
[0039] FIGS. 2 and 3 show that the spigot bearing housing 56 has a
region 57 which is remote from the axis A. The outer edge of the
region 57 is spaced by a distance F1 from the axis A. As shown in
FIG. 2, the distance F1 is greater than the distances E1 and
D1.
[0040] Differential carrier assemblies are known wherein the
equivalent distance E1 is less than the equivalent distance F1 and
wherein the spigot bearing housing is integral with the
differential carrier. Thus, to assemble the differential casing sub
assembly, it is necessary to position the differential casing sub
assembly to the left relative to its final position as the ring
gear tooth apexes pass the spigot bearing housing, and then move
the differential casing sub assembly to the right to mesh the ring
gear with the pinion gear so that the differential casing sub
assembly sits in its correct final position. This requires awkward
maneuvering of the components during assembly and also requires a
clear space envelope to accommodate such maneuvering.
[0041] During the above mentioned assembly process of the present
invention, it is possible to position the spigot bearing housing 56
in the annular recess that is immediately radially inboard of the
ring gear teeth 23 when the common component 70 is loosely
assembled onto the differential casing sub assembly 34 when the
differential casing and bearing housing sub assembly 35 is formed.
By carrying out this operation remote from the differential carrier
60, no awkward maneuvering of the differential casing and bearing
housing sub assembly 35 relative to the differential carrier 60 and
the pinion sub assembly 61 is required at a later stage, thereby
simplifying assembly and minimizing the clear space envelope
requirement.
[0042] An alternative way of assembling the differential carrier 60
is to mount the spigot bearing 54 on the pinion spigot 44 first,
and then the outer race of the spigot bearing 54 will engage with
the spigot bearing housing 56 as the differential casing and
bearing housing sub assembly 35 is mated with the pinion sub
assembly 61.
[0043] The foregoing description is only exemplary of the
principles of the invention. Many modifications and variations are
possible in light of the above teachings. It is, therefore, to be
understood that within the scope of the appended claims, the
invention may be practiced otherwise than using the example
embodiments which have been specifically described. For that reason
the following claims should be studied to determine the true scope
and content of this invention.
* * * * *